The present invention relates to writing implements, and more particularly to a writing tool which externally extends a lead contained within an inner container by a simple knocking operation with a writer""s fingers.
In general, various attempts have been tried to improve efficiency in using a writing tool in which press buttons are provided on a lateral side of the tool and a lead contained within the tool is exposed to the outside by pressing the button with a finger while the tool is held by the remaining fingers.
Such writing tools are provided with means for releasing the lead to expose it to the outside. For instance, when the press button is pressed, a pressing member mounted at an end of the press button depresses an inclined face of the inner container enclosing the lead, and a force exerted on the inclined face moves the inner container relatively forward.
Recently, there have been moves to improve efficiency in dealing with writing tools, in which more than two press buttons are provided on lateral surfaces of a writing tool and the lead contained within the tool is exposed to the outside by pressing either of the buttons with a finger while the tool is held by other fingers.
FIG. 7 illustrates an inside layout of one of the above-described conventional writing tools. As illustrated, two press buttons 53 that can be pressed down when the tool is grasped by fingers, are adapted on lateral sides of an outer container 51 in a symmetrical manner to each other about an axis of the outer container 53. Inside the outer container 51, there is provided an inner container 57 that can be moved forward by press buttons 53, allowing the lead to be exposed to the outside. The inner container 57 includes a conical portion defining an inclined face 59 on which a pressing member 53a of press button 53 comes in contact with the inclined face 59. When the press button 53 is xe2x80x9cknocked,xe2x80x9d the pressing member 53a comes into contact with the inclined face 59 to depressing it, while moving down along inclined face 59, resulting such that inner container 57 moves forward to allow lead 55 to be exposed to the outside.
However, in the configuration of the prior art described above, since a portion of inner container 57 defining the inclined face 59 is a conical shape, symmetrical with respect to an axis of the inner container 57, as illustrated, the inner container 57 is provided with a narrow portion 61 having an excessively narrow outer diameter at a distal end of the inclined face 59.
Further, if a structural change is required to lengthen a travel distance of the inclined face 59 at one knocking operation without modifying an inclined angle of the inclined face 59 with respect to the axis of the inner container 57, the outer diameter of the narrow portion 61 must be seriously decreased.
The inner container 57 having such narrow portion 61 may be easily broken from a moderate external impact or cumulative internal fatigue caused by repeated depressing forces exerted on pressing member 53a on inclined face 59. For these reasons, the choice of suitable materials for conventional inner container 57 in known writing tools are restricted as such materials must have the necessary rigidity to prevent these problems.
As illustrated in the drawing, the narrow portion 61 of the inner container has an outer diameter unduly narrow relative to other portions. In conventional manufacturing processes, it is difficult to produce a resin article such as the inner container having its cross sectional area excessively changed by means of an injection molding. The finished product normally has a deteriorated quality since molten resin for that article cannot actively flow within a mold.
In accordance with the configurations of the prior art, the buttons 53 are arranged on lateral sides of the outer container 51 along one circumferential line. Thus, if the number of buttons 53 increases, the outer container 51 can be mechanically weakened as a plurality of openings 63 through which buttons 53 are positioned must be formed through outer container 51. Further, when a user presses buttons 53 as arranged in the above-described manner, there is an inconvenience as the user has to change finger positions while holding the writing tool to press buttons 53 as the positions of the thumb, index and middle fingers or the like, holding the writing tool are normally positioned on the outer container, being misaligned with the circumferential direction.
It is, therefore, an object of the present invention to provide a writing tool capable of resolving the aforementioned inconveniences in the art, which includes a structurally enhanced member moving in response to movements of a plurality of buttons arranged on lateral sides of the writing tool, whereby choice of raw materials for the tool are not limited and the writing tool has an improved endurance and productivity as the member has excellent properties required in injection molding.
It is another object of the present invention to make it easy for a user to operate the writing tool with her fingers, while holding the writing tool.
To accomplish these objectives, the present invention provides a writing tool comprising, an outer container including a head member in which a hole is formed through which a lead is exposed to the outside; a grip in which a plurality of openings are formed; a plurality of buttons, one portion of each being positioned at each of the plurality of openings, while the other portion being positioned inside the outer container; and an inner container housed within the outer container and provided with a plurality of inclined faces adapted to contact the buttons when the buttons are pressed; wherein the inner container moves forward within the outer container and exposes the stored lead out of the head member when at least one of the buttons is pressed, and the inclined faces are arranged within a predetermined angle therebetween in a circumferential direction of the inner container and are positioned at different places in an axis of the inner container.
Preferably, the predetermined angle between the inclined faces ranges from 110xc2x0 to 165xc2x0; and an inclination angle of the inclined face with respect to the axis of the inner container ranges from 20xc2x0 to 35xc2x0.
The plurality of buttons are angularly spaced apart with a predetermined angle therebetween in a circumferential direction of the outer container, while being positioned at different places in the axis of the outer container, in order to enable the buttons to be depressed by different fingers of a user, when the user holds the outer container.
The writing tool can also comprise an elastic member covering a surface of the grip of the outer container and extending over the openings.